Photo-decomposttion of Fluorocarbons in the Air

Abstract

Air containing one of fluorocarbons (1000 ppm) such as chlorodifluoromethane (CHC1F2), chlorotrifluoromethane (CC1F3), dichlorodifluoromethane (CCl2F2), 1, 1-difluoroethane (C2H4F2), bromochlorodifluoromethane (CBrClF2), bromotrifluoromethane (CBrF3), 2, 2-difluoroethylene (C2H2F2), chlorotrifluoroethylene (C2C1F3) and tetrafluoroethylene (C3F4) was irradiated by mercury lamp at room temperature. In the both cases of CCl2F2 and C2ClF3 the photo-decomposition in the presence of oxygen was faster than that in the absence of oxygen. Both carbon monoxide and carbon dioxide were observed in the irradiated gas. The initial degree of decomposition of fluorocarbons, chlorofluorocarbons, unsaturated fluorocarbons and unsaturated chlorofluorocarbons increased with the decrease in wavelength, and that of bromofluorocarbons with the increase in wavelength. The initial degree of decomposition of C2C1F3 with UV irradiation by a high pressure mercury lamp (100 W) was about 1000 times that of Cl2F3 and about 50 times that of CBrClF2. The photo-oxidative decomposition of C2C1F3 also took place by sun light irradiation, 60% of C2ClF3 disappeared under outdoor exposure within 3 days. While in the case of C2ClF3 the reaction did not occur under outdoor exposure during one week. The reaction of C2C1IF2 was accelerated by both chlorine and ozone, while those of CC12F2 and CBrClF2, were not. On the other hand, CF4 and C2H4F2 scarcely affected the decomposition of ozone, while CBrClF2 and C2ClF3 remarkably accelerated that. In the case of CCl2F2, the initial degree of decomposition of ozone increased proportionally with the increase in the initial concentration of CCl2F2 (log[CCl2F2]). © 1976, The Chemical Society of Japan. All rights reserved.